Barangay Casili

Classified as a very small barangay, Barangay Casili is one of the administrative divisions of Santo Domingo in Ilocos Sur, Ilocos Region, Philippines.

According to the 2020 Philippine census, Barangay Casili had a population of 388. This made it the 32nd largest of 36 barangays in Santo Domingo by population, placing it among the smaller barangays of the municipality. Residents of Barangay Casili accounted for approximately 1.34% of the total population of Santo Domingo, which stood at 29,041 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay Casili changed from 331 to 388, a shift of +17.2% over the five-year period. This places the barangay among those with growing populations in Santo Domingo. Barangay Casili is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Santo Domingo is a municipality comprising 36 barangays, and serves as the governing unit directly responsible for local services in Barangay Casili, including public health, sanitation, peace and order, and civil registration. Within the wider province of Ilocos Sur, which contains 768 barangays across its component cities and municipalities, Barangay Casili ranks 653rd by 2020 population. Ilocos Sur is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Barangay Casili is governed by an elected Sangguniang Barangay composed of a Punong Barangay and seven kagawads, with the Sangguniang Kabataan representing the youth. The next BSKE, set for Monday, November 2, 2026, will elect officials to four-year terms as provided under Republic Act No. 12232.